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PINPOINT TEST A: NO COMMUNICATION WITH THE 4x4 MODULE (PCM)

WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes.
  1. A1 CHECK CAN COMMUNICATION 
    NOTE: To distinguish between a loss of CAN communication to the 4x4 module and a loss of CAN communication with the entire vehicle, the ABS module CAN communication is verified because it uses CAN for diagnostics.
    • Verify CAN communication with the anti-lock brake system (ABS) module.
      • If using the WDS, follow the directions and carry out the network test.
      • If using VCM, verify that the vehicle and engine selection information are correct.
    • Does the scan tool communicate with the ABS module? 

    Yes  GO to A2.

    No  REFER to the appropriate scan tool manual for further diagnosis.

  2. A2 CHECK THE FUSES 
    • Check BJB fuse 18 (20A) and CJB fuse 24 (15A).
    • Are the fuses okay? 

    Yes  GO to A3.

    No  REPAIR as necessary. REPEAT the self-test.

  3. A3 CHECK FOR BATTERY VOLTAGE FROM THE BATTERY JUNCTION BOX (BJB) 
    • Key in ON position.
    • Measure the voltage between BJB input side fuse cavity 15 and ground; measure the voltage between BJB input side fuse cavity 20 and ground.
    • Are the voltages greater than 9 volts? 

    Yes  GO to A4.

    No  REPAIR or INSTALL new components as necessary. REPEAT the self-test.

  4. A4 CHECK FOR VOLTAGE INPUT TO THE 4x4 MODULE (PCM) 
    • Disconnect: 4x4 Control Module (PCM) C175b.
    • Key in ON position.
    • Measure the voltage between 4WD module 175b-49, circuit 729 (RD/WH), harness side and ground; measure the voltage between 4WD module 175b-50 circuit 994 (WH) harness side and ground.
    • Are the voltages greater than 9 volts? 

    Yes  GO to A5.

    No  REPAIR the affected circuit(s). REPEAT the self-test.

  5. A5 CHECK THE GROUND CIRCUITS FOR AN OPEN 
    • Measure the resistance between C175b-47, circuits 570a C175b-48, circuit 570b C175b-49, circuits 570c, (BK/WH) and ground.
    • Are the resistances less than 5 ohms? 

    Yes  GO to A6.

    No  REPAIR the affected circuit(s). REPEAT self-test.

  6. A6 CHECK THE BATTERY VOLTAGE WITH THE ENGINE RUNNING 
    • Start the engine.
    • Measure the battery voltage at the positive battery terminal.
    • Is the voltage greater than 9 volts? 

    Yes  INSTALL a new 4x4 module (PCM). REFER to INTAKE AIR, FUEL CHARGING, STARTING AND ENGINE ELECTRONICS - 4.0L SOHC or INTAKE AIR, FUEL CHARGING, STARTING AND ENGINE ELECTRONICS -4.6L (2V) . REPEAT the self-test.

    No  CHECK the charging system. REFER to BATTERY & CHARGING SYSTEM .

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